Fluid flow control apparatus is well known in the art. Generally, apparatus of this type either counts drops of fluid which is dispensed, or it is arranged to respond when the fluid source is empty. None of the prior art apparatus has the advantage of the present invention in which the alarm fluid level can be readily adjusted and detected, and in which the period of time following such detection in which some fluid is still available is controllable. In a medical application, this available time period permits a nurse to respond to the alarm and to replace the fluid supply.